[WIP/RFC] MIPS registers overhaul

Andrew Cagney ac131313@redhat.com
Wed May 21 16:38:00 GMT 2003


>> That came out wrong.
>> 
>> I think a GDB debugging a remote 64 bit MIPS ISA should always expect 64 
>> bit GPRs and 64 bit FPRs when the ISA is 64 bits, regardless of the ABI.
>> 
>> It is quite legitimate, for instance, for GDB to do something as sick-o 
>> as clearing the FR bit and then resume the thread.  The register 
>> save/restore code needs to correctly handle this - be it reject the 
>> operation or ``do the right thing''.
> 
> 
> But when using rda or gdbserver to debug an o32 application, then for
> all intents and purposes we are debugging a 32-bit ISA.  The kernel
> will not allow us to change the FR bit.  The app will never see 64-bit
> registers.  The 32-bit protocol makes more sense here IMO.

 From GDB's view point, the ISA is 64 bit.

The fact that a specific remote debug agent choses to use 32 bit 
registers is a limitation of that debug agent / kernel.  An embedded 
target, and I'm pretty sure IRIX 6.5, for instance, don't do that.

Andrew




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